Exam 3: Causality

Question 1

What are Koch’s postulates?

Answer 1

An organism is causal if:
It is present in all cases of the disease
It does not occur as fortuitous or non-pathogenic parasite
It is isolated in pure culture from a case
Organism can be repeatedly passaged and induces the same disease in other animals

Question 2

What are problems with Koch’s postulates today?

Answer 2

Multiple etiologic factors
Multiple effects of a single cause
Asymptomatic carriers
Non agent factors such as age
Immunologic processes as cause of disease
Host-agent, host-environment interactions
Noninfectious causes of disease

Question 3

What is the surgeon general’s criteria?

Answer 3

Consistency
Strength of association
Specificity of outcome, time, place, population
Temporality
Coherence

Question 4

What is Hills criteria?

Answer 4

Surgeon general criteria plus:
Dose-response relationship
Plausible biologic mechanism
Experimental evidence to compliment

Question 5

What did the surgeon general and hills criteria acknowledge?

Answer 5

That clinically healthy individuals frequently tolerate pathogens quite well

Question 6

What did surgeon general and hill criteria require?

Answer 6

Proof of an association between hypothesized causal factor and the disease

Question 7

What did the surgeon general and hills criteria accomodate for?

Answer 7

Non-infectious factors

Question 8

What did the surgeon general and hills criteria mandate?

Answer 8

Temporal sequence

Question 9

What does the dose-response relationship with surgeon general and hills criteria do?

Answer 9

Adds credibility